The dissociation stuff means that the faculties of your mind are pulling back a little to disconnect you from potential pain. For me, it has manifested in four ways:

a) Out of body experience. You only remember or see things as if you were looking down on yourself from the ceiling. I experienced this when I cut myself.
b) Spacing out. Having trouble connecting with others because you're stuck in your head.
c) Extreme spacing out. This happens a lot to me during sex. I'll be having sex and then I don't know where I go, but my body does all the work still. It's like blacking out.
d) The Bell Jar (thanks Plath!). You literally feel that there is an invisible boundary between you and everyone else. I tend to feel this way if people don't understand me or invalidate my feelings, esp when they say something like "we don't want to talk about that."

I can't speak for everyone, but I hope this helps.